Multiple stage vapor condensing unit

ABSTRACT

A multiple stage vapor condensing unit including a housing formed with respective high and low pressure condensing chambers which feed into respective high and low pressure demister chambers. Disposed beneath the respective demister chambers are respective fluid collection chambers. Vapor condensing means is disposed in the respective vapor condenser chambers and demister means is disposed in the respective demister chambers whereby vapor from a fuel tank may be fed through the low pressure condenser chamber to the low pressure demister chamber to condense a portion of such vapor and collect the resulting fluid in the low pressure fluid collection chamber. The vapor emitting from the low pressure demister chamber may then be compressed and fed through the high pressure condenser chamber to the high pressure demister chamber where additional vapor is condensed to produce fluid for collection in the high pressure fluid chamber.

1 51 July 25,1972

ABSTRACT A multiple stage vapor condensing unit including a housing 7 Claims, 1 Drawing Figure Primary Examiner-Frank W. Lutter Assistant ExaminerVincent Gifford Attorney-Fu1wider, Patton, Rieber, Lee & Utecht formed with respective high and low pressure condensing chambers which feed into respective high and low pressure demister chambers. Disposed beneath the respective demister chambers are respective fluid collection chambers. Vapor condensing means is disposed in the respective vapor condenser chambers and demister means is disposed in the respective demister chambers whereby vapor from a fuel tank may be fed through the low pressure condenser chamber to the low pressure demister chamber to condense a portion of such vapor and collect the resulting fluid in the low pressure fluid collection chamber. The vapor emitting from the low pressure demister chamber may then be compressed and fed through the high pressure condenser chamber to the high pressure demister chamber where additional vapor is condensed to produce fluid for collection in the high pressure fluid chamber.

343, 223, 228, DIG. 25, 316

.55/269, 55/219, 55/277, 55/322, 55/342, 55/DIG. 25, 220/85 VS .B0ld 50/00 .62/54; 220/85 S, 85 US, 85 VR;

..55/222 UX .55/277 X .....220/85 U .....55/277 X ....55/268 X Edwin R. Davis, 2020 Beverly Plaza, Apt. 213, Long Beach, Calif. 90815 Sept. 10, 1970 References Cited UNITED STATES PATENTS 074 6/1935 133 Tompkins... Pennington l-lankison et a1.

United States Patent Davis [54] MULTIPLE STAGE VAPOR CONDENSING UNIT [72] Inventor:

22 Filed:

21 Appl.No.:

[52] [58] FieldofSearch.............

1 lllllla III. 40 L 4 2 3 i.lilsanl-illal llllrllillinl N iiiiiiiiiiiiii i llllllllllllll r1 FUEL TANK Patented July 25, 1972 3,678,661

INVENTOR EDWIN R DAV/5 BY {M 7?.

MULTIPLE STAGE VAPOR CONDENSING UNIT BACKGROUND OF THE INVENTION 1. Field of the Invention The multiple stage vapor condensing unit of present invention relates to condensers for condensing the hydrocarbons out of vapor emitted from a fuel tank to conserve such fuel and prevent emission of hydrocarbons to the atmosphere.

2. Description of the Prior Art Vapor recovery systems have been proposed which include multiple stage chillers as disclosed in US. Pat. No. 3,266,262. Vapor recovery units of this type are generally impractical for meeting the stringent requirements of many local laws since the power required to chill such vapors to a sufficiently low level to condense nearly all the hydrocarbons out of the fuel vapor before it is emitted to the atmosphere renders such units too expensive to be practical to operate. Vapor recovery units have also been proposed which include condensers and cooling coils. A unit of this type is shown in US. Pat. No. 3,369,371. Vapor recovery units of this type suffer the shortcoming that they are not of unitary construction and are rela' tively cumbersome and occupy such a large amount of space as to be relatively impractical for installation in gas stations where the space available is severly limited.

SUMMARY OF THE INVENTION The multiple stage vapor condensing unit of present invention is characterized by a unitary housing formed with high and low pressure condenser chambers which are in communication with respective high and low pressure demister chambers. Disposed below the demister chambers are fluid collection chambers. Condensing means is disposed in the respective condenser chambers and demister means is disposed in the respective demister chambers whereby fuel vapor may be introduced to the low pressure condensing chamber to initiate condensation thereof and such vapor may then be passed on to the low pressure demister chamber where the fluid is separated from the vapor for collection in the low pressure fluid collection chamber. The vapor emitting from the low pressure demister chamber may than be compressed and introduced to the high pressure condenser chamber for passage therethrough and introduction to the high pressure demister chamber for separation of additional fluid from the vapor for collection in the high pressure fluid collection chamber.

An object of the present invention is to provide a multiple stage vapor condensing unit which is relatively compact for convenient installation in locations having relatively restricted area.

Another object of the present invention is to provide a multiple stage vapor condensing unit of the type described wherein the vapor is expanded in condenser chambers and such chambers are disposed in heat exchange relationship with one another for mutual cooling of one another.

These and other objects and the advantages of the present invention will become apparent from a consideration of the following detailed description taken in conjunction with the accompanying drawing.

DESCRIPTION OF THE DRAWING The single FIGURE shows a multiple stage vapor condensing unit embodying the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The multiple stage vapor condensing unit of present invention includes, generally, a housing 7 formed with respective low and high pressure condenser chambers which have respective vertically extending parallel low and high pressure condensing tubes and 6 mounted therein. The lower extremity of low and high pressure tubes 5 and 6 are connected with respective demister chambers which include demisters l9 and for separating fluid droplets out of the vapor for collection in fluid collection chambers 35' and 36' formed by the lower portion of such chambers. Thus, fuel vapor may be introduced to the upper ends of the low pressure condensing tubes 5 and passed therethrough to initiate condensation thereof and such vapor will pass through the demister 19 to separate the condensed fluid from the vapor for collection in the lower pressure fluid collection chamber 35. The separated vapor may then be compressed and introduced to the upper ends of the high pressure condensing tubes 6 and passed downwardly therethrough to effect further condensing and such vapor may then be passed through the high pressure demister 20 to further separate the condensed fuel thereof for collection in the high pressure fluid collection chamber 36'.

The housing 7 includes a low pressure condensing chamber inlet 1 which may be connected with a compresser l' receiving vapor expelled from a fuel tank. The inlet 1 is formed by an inlet header 2 which has a central partition 3 therein for separating the low pressure inlet 1 from a high pressure inlet 4. The inlet header 2 is mounted to the upper end of the housing 7 by means of mounting bolts 8 which project through the mounting flanges of such header and the housing 7, such flanges having a sealing gasket 9 sandwiched therebetween. The housing 7 forms a coolant chamber surrounding the respective low and high pressure condensing tubes 5 and 6 and is formed in its lower extremity with a coolant inlet 10 and in its upper extremity with a coolant outlet 11. Such housing 7 is formed intermediately with a radially projecting convolusion forming expansion bellows 12.

The lower extremity of the housing 7 is formed with radially projecting mounting flanges which have mounting bolts 13 projected therethrough for connection with a mating mounting flange formed by the upper extremity of a demister housing 14, a sealing flange 15 being sandwiched between such mounting flanges.

The demister housing 14 includes a central partition 16 which separates such housing into the respective low and high pressure demister chambers for receiving the respective demisters 19 and 20. Downwardly extending deflector flanges 17 and 18 cooperate with the partition 16 to form the inlet to the respective demister chambers and form a vapor flow path which defines a substantially reverse turn about their lower extremities. The demisters 19 and 20 are formed by steel wool sandwiched between upper and lower screens to thereby provide means for coalescing minute vapor droplets into larger droplets for collection in the fluid chambers 35 and 36'. Disposed vertically above the demisters l9 and 20 are respective vibrating reeds 19a and 20a which vibrate at the natural frequency of the fuel droplets in the vapor to thereby cause such droplets to vibrate and coalesce thereby forming larger droplets which will drop downwardly into the fluid collection chambers 35' and 36'.

The low and high pressure demister chambers have respective outlets 21 and 22 for passage of the vapor from which the fluid has been separated.

Float valves 23 and 24 are provided for controlling flow to the outlets 33 and 34 of the fluid collection chambers 35 and 36'. The respective float valves 23 and 24 include respective lever arms 25 and 26 which are pivotally connected with respective poppets 29 and 30 by means of respective pivot pins 27 and 28. Adjustment screws 45 and 46 are provided for engaging the respective ends of the lever arms 25 and 26 opposite the valve floats 23 and 24. The poppets 29 and 30 selectively seat on respective valve seats 31 and 32 controlling flow out the respective outlets 33 and 34. Filters in the form of screen cages 35 and 36 surrounding the float balls 23 and 24 are provided for protecting the respective valves from damage by solids collected in the chambers 35 and 36.

The float valves 23 and 24 are carried in respective valve housings 37 and 38 which are secured to the demister housing 14 by means of respective mounting bolts 39 and 40, respective seals 41 and 42 being sandwiched between such valve housings and the demister housing 14 to prevent leakage.

Clean-out plugs 43 and 44 are provided in the bottom of the respective fluid collection chambers 35 and 36 whereby residue collected therein may be removed. A compressor 21 has its inlet connected with the low pressure demister chamber outlet 21 and has its outlet connected with the high pressure condensing chamber inlet 4.

In operation, the first stage compresser 1' has its inlet connected with the upper portion of a fuel tank for receipt of vapors created therein when such tank is filled with fuel or when atmospheric heating causes additional vaporization thereof. The compressor 1 may have its controls connected with a pressure responsive means sensing pressure in the fuel tank whereby it will be actuated when a predetermined vapor pressure is reached in such tank. The compresser 1 will compress the fuel vapor to approximately 68 pounds per square inch gage and raise its temperature to approximately 250 F. Such vapor is then released into the low pressure condensation tubes where it is expanded and cooled to approximately 60 F. to initiate condensation. The vapor flowing downwardly through such tubes will condense out on the walls thereof and the condensation will pour downwardly to pass, along with the vapor, into the low pressure demister chamber to collect in the low pressure fluid collection chamber 35 until the level thereof raises sufficiently to raise the float valve 23 and raise the poppet 29 off its seat 31 to allow the fluid to flow out the outlet 33 from where it may be returned to the fuel tank.

The vapor flowing downwardly into the demister chamber will turn upwardly around the lower extremity of the deflector 17 to pass through the demister 19 which provides a substantial amount of surface area for inducing further condensation of such vapor. The fluid condensed out in the demister 19 will also pour downwardly into the fluid collection chamber 35'. Additionally, the vapor flowing upwardly through the demister 19 will encounter the vibrations set up by the vibrating reeds 19a to cause the minute droplets in such vapors to coalesce and form larger droplets which will be drawn downwardly into the fluid collection chambers 35 by means of gravity.

The vapor passing out through the low pressure demister chamber outlet 21 will be introduced to the inlet of the second stage compressor 21' where it will be compressed to approximately 415 P810 and 350 F. The compressed vapor emitted from the compresser 21' will be introduced to the upper ends of the high pressure condensing tubes 6 where it will be expanded and cooled to approximately 60 F. to cause such vapor to condense on the surface of such tubes and pour downwardly into the high pressure fluid collection chamber 36. It is a particular importance that the condenser tubes 5 and 6 are disposed in heat exchange relationship with one another to thereby effect heat exchange therebetween and take advantage of the cooling effect of the expanding vapor to maintain the vapor in such tubes relatively cold. The remaining vapor passing downwardly into the high pressure demister chamber will reverse its flow direction about the lower extremity of the deflector 18 to cause addition amounts of fluid to be separated therefrom by means of centrifugal force and the remaining vapor will flow upwardly through the demister where additional amounts of such vapor will be condensed on the surface areas thereof. The vapor flowing upwardly through the demister 20 will be exposed to the vibrations of the vibrating reeds 20a and will be coalesced thereby to form larger droplets which will pour downwardly into the fluid collection chamber 36'. When the fluid level in the collection chamber 36' raises sufficiently, the flow valve will be opened and fluid will flow outwardly past the valve seats 32 and out the outlet 34 from where it may be returned to the fuel tanks.

From the foregoing it will be apparent that the multiple stage fuel condensing unit of present invention is a relatively compact unit for effecting efficient and thorough condensing of the vapors emitted from a fuel tank to thereby condense the fuel therefrom and provide unpolluted vapor for emission to the atmosphere. The compactness and close positioning of the individual chambers prevents excessive warming of the va or that passes from one chamber to the other thereby enab ing such vapors to be maintained relatively cold to assure substantially complete condensation of the hydrocarbons from the fuel vapor.

Various modifications and changes may be made with regard to the foregoing detailed description without departing from the spirit of the invention.

I claim:

1. A multiple stage vapor condensing unit comprising:

a housing formed with high and low pressure condenser chambers having respective inlets and outlets, said housing including high and low pressure demister chambers including respective inlets connected with the outlets of said respective high and low pressure condenser chambers and having respective high and low pressure demister vapor and liquid outlets, said housing further including high and low pressure fluid collection chambers in direct flow communication with said respective high and low pressure demister liquid outlets;

condensing means disposed in said high and low pressure condenser chambers; and

demister means in said respective high and low pressure demister chambers whereby said low pressure condensing chamber inlet is connected with the upper portion of a hydrocarbon fuel tank, said vapor outlet from said low pressure demister chamber connected through a compresser to the inlet to said high pressure condenser chamber, said fluid collection chambers connected with said fuel tank and fuel vapor emitted from said fuel tank will be passed through said low pressure condenser chamber to condense a portion of said vapor and said vapor will then be passed through said low pressure demister chamber to condense fluid from said vapor and collect it in said low pressure fluid collection chamber, said vapor then passed on through said condenser to said high pressure condenser chamber to condense more fluid therefrom and then through said high pressure demister chamber to extract additional fluid therefrom for deposit in said high pressure fluid collection chamber for return to said fuel tank.

2. A multiple stage vapor condensing unit as set forth in claim 1 wherein:

said high and low pressure condenser chambers are disposed in heat exchange relationship with one another.

3. A multiple stage vapor condensing unit as set forth in claim 1 wherein:

said condensing means includes a plurality of vertically extending conduit members for passage of said vapor.

4. A multiple stage vapor condensing unit as set forth in claim 1 wherein:

said demister means includes vibrating reed means for vibrating at substantially the natural frequency of the fluid in said vapor.

5. A muln'ple stage vapor condensing unit as set forth in claim 1 wherein:

said demister chambers include a flow path formed with a substantially reverse turn to induce the condensation of said vapor as it flows therethrough.

6. A multiple stage vapor condensing unit as set forth in claim 1 wherein:

said respective high and low pressure condenser chambers,

demister chambers and fluid collection chambers are arranged in substantially vertical alignment whereby fluid condensed out of said vapor will fall downwardly into said respective collection chambers.

7. A multiple stage vapor condensing unit as set forth in claim 1 wherein said housing includes:

cooling means disposed in heat exchange relationship with said condenser means. 

1. A multiple stage vapor condensing unit comprising: a housing formed with high and low pressure condenser chambers having respective inlets and outlets, said housing including high and low pressure demister chambers including respective inlets connected with the outlets of said respective high and low pressure condenser chambers and having respective high and low pressure demister vapor and liquid outlets, said housing further including high and low pressure fluid collection chambers in direct flow communication with said respective high and low pressure demister liquid outlets; condensing means disposed in said high and low pressure condenser chambers; and demister means in said respective high and low pressure demister chambers whereby said low pressure condensing chamber inlet is connected with the upper portion of a hydrocarbon fuel tank, said vapor outlet from said low pressure demister chamber connected through a compresser to the inlet to said high pressure condenser chamber, said fluid collection chambers connected with said fuel tank and fuel vapor emitted from said fuel tank will be passed through said low pressure condenser chamber to condense a portion of said vapor and said vapor will then be passed through said low pressure demister chamber to condense fluid from said vapor and collect it in said low pressure fluid collection chamber, said vapor then passed on through said condenser to said high pressure condenser chamber to condense more fluid therefrom and then through said high pressure demister chamber to extract additional fluid therefrom for deposit in said high pressure Fluid collection chamber for return to said fuel tank.
 2. A multiple stage vapor condensing unit as set forth in claim 1 wherein: said high and low pressure condenser chambers are disposed in heat exchange relationship with one another.
 3. A multiple stage vapor condensing unit as set forth in claim 1 wherein: said condensing means includes a plurality of vertically extending conduit members for passage of said vapor.
 4. A multiple stage vapor condensing unit as set forth in claim 1 wherein: said demister means includes vibrating reed means for vibrating at substantially the natural frequency of the fluid in said vapor.
 5. A multiple stage vapor condensing unit as set forth in claim 1 wherein: said demister chambers include a flow path formed with a substantially reverse turn to induce the condensation of said vapor as it flows therethrough.
 6. A multiple stage vapor condensing unit as set forth in claim 1 wherein: said respective high and low pressure condenser chambers, demister chambers and fluid collection chambers are arranged in substantially vertical alignment whereby fluid condensed out of said vapor will fall downwardly into said respective collection chambers.
 7. A multiple stage vapor condensing unit as set forth in claim 1 wherein said housing includes: cooling means disposed in heat exchange relationship with said condenser means. 